In the wireless communication system, a spatial multiplexing mode is adopted between a sending end and a receiving end and multiple antennas are used to obtain higher transmission rate. The common spatial multiplexing technology based on the closed loop feedback can be described as that: the receiving end feeds back the channel state information (abbreviated as CSI) to the sending end, the sending end uses some transmission precoding technologies according to the acquired channel information, and thus the transmission performance is greatly improved.
However, in the real application, the closed loop spatial multiplexing technology is not applicable sometimes; for example, the link quality of the uplink feedback is poor and the channel information cannot be fed back accurately. Again for example, the movement speed of the terminal is very fast, so the channel between the base station and the terminal changes very fast (the movement leads to the Doppler frequency shift, and brings the changes on the time domain); the time delay brought by the feedback link and the schedule, etc., makes the fed back CSI information of the previous channel be unable to represent the real-time channel information very well, which causes mismatching of the precoding. In this case, the open loop spatial multiplexing can support the space multiplexing well in the case of not obtaining the channel state information.
The current open loop spatial multiplexing technology only supports the situation of a single user, for example, in the long term evolution (abbreviated as LTE), the specified open loop precoding technology is:
      [                                                      y                              (                0                )                                      ⁡                          (              i              )                                                            ⋮                                                                y                              (                                  P                  -                  1                                )                                      ⁡                          (              i              )                                            ]    =            W      ⁡              (        i        )              ⁢          D      ⁡              (        i        )              ⁢          U      ⁡              [                                                                              x                                      (                    0                    )                                                  ⁡                                  (                  i                  )                                                                                        ⋮                                                                                            x                                      (                                          υ                      -                      1                                        )                                                  ⁡                                  (                  i                  )                                                                    ]            
Wherein,
      [                                                      x                              (                0                )                                      ⁡                          (              i              )                                                            ⋮                                                                x                              (                                  υ                  -                  1                                )                                      ⁡                          (              i              )                                            ]     is a symbol to be sent, υ is the number of layers of the transmission data, U matrix is a matrix related to the number of layers υ, D(i) is a matrix related to a frequency location i and the number of layers υ. U and D(i) are shown in the following table:
TABLE 1The number oflayers υUD(i)2      1          2        ⁡      [                            1                          1                                      1                                      e                                          -                j                            ⁢                                                          ⁢              2              ⁢                              π                /                2                                                          ]        [                            1                          0                                      0                                      e                                          -                j                            ⁢                                                          ⁢              2              ⁢              π              ⁢                                                          ⁢                              i                /                2                                                          ]      3      1          3        ⁡      [                            1                          1                          1                                      1                                      e                                          -                j                            ⁢                                                          ⁢              2              ⁢                              π                /                3                                                                          e                                          -                j                            ⁢                                                          ⁢              4              ⁢                              π                /                3                                                                          1                                      e                                          -                j                            ⁢                                                          ⁢              4              ⁢                              π                /                3                                                                          e                                          -                j                            ⁢                                                          ⁢              8              ⁢                              π                /                3                                                          ]        [                            1                          0                          0                                      0                                      e                                          -                j                            ⁢                                                          ⁢              2              ⁢              π              ⁢                                                          ⁢                              i                /                3                                                              0                                      0                          0                                      e                                          -                j                            ⁢                                                          ⁢              4              ⁢              π              ⁢                                                          ⁢                              i                /                3                                                          ]      4      1    2    ⁡      [                            1                          1                          1                          1                                      1                                      e                                          -                j                            ⁢                                                          ⁢              2              ⁢                              π                /                4                                                                          e                                          -                j                            ⁢                                                          ⁢              4              ⁢                              π                /                4                                                                          e                                          -                j                            ⁢                                                          ⁢              6              ⁢                              π                /                4                                                                          1                                      e                                          -                j                            ⁢                                                          ⁢              4              ⁢                              π                /                4                                                                          e                                          -                j                            ⁢                                                          ⁢              8              ⁢                              π                /                4                                                                          e                                          -                j                            ⁢                                                          ⁢              12              ⁢                              π                /                4                                                                          1                                      e                                          -                j                            ⁢                                                          ⁢              6              ⁢                              π                /                4                                                                          e                                          -                j                            ⁢                                                          ⁢              12              ⁢                              π                /                4                                                                          e                                          -                j                            ⁢                                                          ⁢              18              ⁢                              π                /                4                                                          ]        [                            1                          0                          0                          0                                      0                                      e                                          -                j                            ⁢                                                          ⁢              2              ⁢              π              ⁢                                                          ⁢                              i                /                4                                                              0                          0                                      0                          0                                      e                                          -                j                            ⁢                                                          ⁢              4              ⁢              π              ⁢                                                          ⁢                              i                /                4                                                              0                                      0                          0                          0                                      e                                          -                j                            ⁢                                                          ⁢              6              ⁢              π              ⁢                                                          ⁢                              i                /                4                                                          ]     
W(i) is a matrix related to the frequency location i and the number of layers υ. When the number of transmission antennas is 2, W(i) is a fixed 2×2 unit matrix; when the number of transmission antennas is 4, the value of the W(i) can be C1, C2, C3, C4, and the specific value is related to the value of i; the C1, C2, C3, C4 are the code words of which the indexes corresponding to the υ layers are 12, 13, 14 and 15 in the 4 antennas codebook (table 2).
TABLE 2The number of layers νIndexun12340u0 = [1 −1 −1 −1]TW0{1}W0{14}/{square root over (2)}W0{124}/{square root over (3)}W0{1234}/21u1 = [1 −j 1 j]TW1{1}W1{12}/{square root over (2)}W1{123}/{square root over (3)}W1{1234}/22u2 = [1 1 −1 1]TW2{1}W2{12}/{square root over (2)}W2{123}/{square root over (3)}W2{3214}/23u3 = [1 j 1 −j]TW3{1}W3{12}/{square root over (2)}W3{123}/{square root over (3)}W3{3214}/24u4 = [1 (−1 − j)/{square root over (2)} −j (1 − j)/{square root over (2)}]TW4{1}W4{14}/{square root over (2)}W4{124}/{square root over (3)}W4{1234}/25u5 = [1 (1 − j)/{square root over (2)} j (−1 − j)/{square root over (2)}]TW5{1}W5{14}/{square root over (2)}W5{124}/{square root over (3)}W5{1234}/26u6 = [1 (1 + j)/{square root over (2)} −j (−1 + j)/{square root over (2)}]TW6{1}W6{13}/{square root over (2)}W6{134}/{square root over (3)}W6{1324}/27u7 = [1 (−1 + j)/{square root over (2)} j (1 + j)/{square root over (2)}]TW7{1}W7{13}/{square root over (2)}W7{134}/{square root over (3)}W7{1324}/28u8 = [1 −1 1 1]TW8{1}W8{12}/{square root over (2)}W8{124}/{square root over (3)}W8{1234}/29u9 = [1 −j −1 −j]TW9{1}W9{14}/{square root over (2)}W9{134}/{square root over (3)}W9{1234}/210u10 = [1 1 1 −1]TW10{1}W10{13}/{square root over (2)}W10{123}/{square root over (3)}W10{1324}/211u11 = [1 j −1 j]TW11{1}W11{13}/{square root over (2)}W11{134}/{square root over (3)}W11{1324}/212u12 = [1 −1 −1 1]TW12{1}W12{12}/{square root over (2)}W12{123}/{square root over (3)}W12{1234}/213u13 = [1 −1 1 1]TW13{1}W13{13}/{square root over (2)}W13{123}/{square root over (3)}W13{1324}/214u14 = [1 1 −1 −1]TW14{1}W14{13}/{square root over (2)}W14{123}/{square root over (3)}W14{3214}/215u15 = [1 1 1 1]TW15{1}W15{12}/{square root over (2)}W15{123}/{square root over (3)}W15{1234}/2
Wherein, Wn=I−2ununH/unHun, I is a unit matrix, Wk(j) represents the jth column vector of the matrix Wk. Wk(j1,j2, . . . jn) represents a matrix composed by the j1th, j2th, . . . jnth columns of the matrix Wk.